sd transcripts are observed in many cells in the developing embryo. Elevated levels are seen in the heart region of the dorsal vessel and in somatic muscle in stage 13 embryos. Elevated
sd levels are no longer seen in somatic muscle by stage 16. Expression is observed in the salivary glands at stage 16.
sd expression is first observed in embryos at stage 9 in cephalic neuroblasts. Expression continues weakly in the CNS throughout embryogenesis and includes sheath cells. Expression in the PNS is first observed at stage 11. By stage 14, intense staining is seen in ventral and lateral sense organs along the trunk and in the antennomaxillary complex. During head involution, strong expression is observed in the antennomaxillary complex and in the labral sense organs. In larvae, expression is observed in a restricted set of cells in the optic proliferation centers, the cerebral hemispheres and the ventral ganglion. The cells are probably not neuroblasts and may be glia or sheath cells.
sd expression is observed in all of the imaginal discs except the labial disc. Expression in the wing disc occurs in regions that will give rise to the adult wing blade, the scutellum, and the mesopleura. In the eye disc, expression initiates immediately behind the morphogenetic furrow. In adults,
sd expression is observed in discrete regions of the adult brain including cell bodies in the suboesophageal ganglion, nuclei lying medial to the antennal neuropile and within the lobular plate, cell bodies in the calyx of the mushroom bodies and cell bodies in the protocerebrum. Expression is also observed in the proboscis in two cells per sensillum that are thought to be the sheath cell and the glial cell. The sacculus and a subset of cells in the olfactory sensilla show expression as well as photoreceptor cells and restricted cells in the ventral ganglion. Finally, expression is observed in the jump muscle and in hairs located all over the adult cuticle. The expression pattern was observed from in situ hybridization experiments and deduced from the enhancer trap expression pattern. The probe used does not distinguish between
sd transcripts.
sd transcripts are detected in RNA from embryos, larvae, and adults.
